Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Thickness Variation Check






Thickness variation can be checked by measuring the thickness of the rotor at four or more points around its circumference with J 26900-1 or equivalent outside micrometer. All measurements must be made at the same distance in from the edge of the rotor.

A rotor that varies more than specifications can cause pedal pulsation and/or front end vibration during brake applications. A rotor that does not meet these specifications should be refinished to specifications or replaced.

Rotor Thickness Variation (Maximum): 0.013 mm (0.0005 inch)